This invention relates to magnetic disc drive assemblies of the class employing a stack of rigid discs in a standard housing profile.
Magnetic disc drive assemblies employing rigid, or hard, discs are commonly used in desktop and other computer mainframes as a principal memory for the computer. Currently, rigid disc magnetic disc drive assemblies are available in three different standard footprints, commonly known as 2 1/2 inch, 3 1/2 inch and 5 1/4 inch drives. Each of these standard drives are available in several configurations, the most common being known as low-profile and half-high drives. The principal difference between a low-profile drive and a half-high drive is that a low-profile drive typically has half the number of rigid discs in the disc stack, and hence half the data storage capacity, as a half-high drive. Computer manufacturers design their computer models to accommodate one of these three standard footprints and one of the two configurations. Consequently, disc drive manufacturers produce disc drives having a form and fit meeting the standard configuration of one of the three footprints and one of the two heights.
There is a continuing need for faster computers with greater capacity. One technique for meeting this need is described herein by decreasing the size of the recording discs without correspondingly decreasing the size of the housing. To maintain the same disc capacity, a greater number of discs is employed, resulting in a taller disc stack. To maintain the height of the disc drive within the standard configuration, it is necessary that the disc drive housing be thinner than prior housings and that the connections to external circuits be more compactly assembled to the disc drive housing. There is a need, however, for a mechanism to maintain the structural integrity of the disc drive housing without addition of new space-consuming components.
Most disc drives employ desiccants and desiccant housings to maintain the environment within the drive at a suitably low humidity. Since most disc drives are sealed from external environmental conditions, the desiccant serves to maintain the low humidity, regardless of the environmental conditions outside the drive. However, the desiccant packages have a life, dependent on the amount of moisture absorbed. Once the design maximum amount of moisture is absorbed, the desiccant package is no longer useful, and the disc drive is in risk of being subject to too much humidity which can adversely affect the performance of the drive.
One problem of the prior drives is that the desiccant package had to be inserted into the drive before writing servo tracks to the servo surface and before final testing of the drive. Only after completion of these operations could the drive be closed and sealed. During the servo writing and testing operations, the desiccant package was exposed to the high humidity of the surrounding environment, thereby adversely affecting the life of the desiccant package. There is a need, therefore for a desiccant housing within a disc drive that permits insertion of the desiccant package immediately before sealing the drive, thereby prolonging the life of the desiccant package to a maximum extent.